Context-dependent interaction between goal-directed and habitual control under time pressure.

Current theories of habitual behaviour assume that habits and goal-directed actions are controlled by two separate but interacting systems. However, it is not clear how these systems interact when actions must be made under time pressure. We use a task that induces habitual action sequences while requiring participants to perform goal-directed actions that are either congruent or incongruent with the habit. This task allows for the concurrent measurement of goal-directed and habitual behaviour, permitting a nuanced analysis of the interaction between these two control modes in a sample of 60 participants (30 male and 30 female). Using computational modelling, we find that models in which habit influence depends on the number of repetitions explain participant behaviour better than models assuming constant habit strength. We further show that participants modulate their use of the habit depending on the context: they selectively inhibited the habit when it was incongruent with their explicit goals and exploited it when the two were congruent. Drift-diffusion modelling of choices and reaction times shows a shift in response-bias when habits and goals align. Together, our results indicate that habitual and goal-directed actions interact in a context-dependent manner allowing for the adaptive allocation of proactive and reactive control.